Random access refers to a process of setting up a radio link between a terminal device and a network. The terminal device performs uplink synchronization with a network device by using random access. The network device and the terminal device can perform conventional data transmission between each other after a random access procedure is completed.
The random access procedure is mainly intended to: (1) perform uplink synchronization by the terminal device; and (2) allocate a unique identifier to the terminal device by the network device, to facilitate cell scheduling. In addition, in the random access procedure, the terminal device may request the network device to perform uplink data scheduling. Based on a data transmission type and a buffer data size that are reported by the terminal device in a random access request, the network device may schedule an appropriate time-frequency resource for the terminal device to send uplink data.
In the existing random access procedure, the network device allocates an uplink resource to the terminal device based on a default status when an uplink transmission capability of the terminal device is not considered. Default resource allocation is relatively conservative and has low transmission efficiency. If the uplink transmission capability of the terminal device is considered, the terminal device needs to report the uplink transmission capability of the terminal device to the network device for uplink resource allocation. This requires corresponding signaling overheads and is time-consuming, thereby affecting user experience.